The present invention relates to an alarm mechanism in an alarm clock.
Conventionally, an alarm mechanism has been arranged such that cam grooves are formed in an alarm wheel on which an alarm hand is attached, and cam pawls are projectingly provided on a gear of an hour wheel on which an hour hand is attached, so that when a setting alarm time is reached, the cam grooves of the alarm wheel are made to engage with the cam pawls of the gear of the hour hand by the spring force of a plate spring elastically abutting against the alarm wheel, thereby causing an alarm sound.
During the process of assembling a clock, the work of attaching hands in the prior art clock having an alarm mechanism has been performed through the steps that the cam grooves of the alarm wheel are made to engage with the cam pawls of an hour wheel by rotating the hands, and the alarm and hour hands are attached onto the alarm and hour wheels respectively with predetermined positional relationships while holding the state of above-mentioned engagement between the cam grooves and cam pawls. In addition to the foregoing steps, it has been required to perform adjustment work by rotating the hands. This is because it is necessary to perform not only the positional adjustment between the cam grooves of the alarm wheel and the cam pawls of the hour wheel but the positional adjustment among the cams and the alarm and hour hands. However, in the actual circumstances, the operation of adjusting the position of an alarm hand is troublesome to causes an obstacle in the process of assembling a clock. Further, in the repairing of a clock, if an alarm hand or an hour hand comes off from an alarm wheel pipe or an hour wheel pipe, the reattachment work is very difficult in that one must perform the position adjustment in the same manner as described above.
An object of the present invention is to provide an alarm mechanism in which the foregoing positional adjusting operation can be extremely easily carried out and in which the accuracy in alarm setting is high.
The present invention is characterized in that in an alarm hand and an hour hand which are provided coaxially with each other, in contacting portions between respective hub portions of the alarm and hour hands, cam grooves and cam pawls are respectively formed on one and the other of the respective hub portions, and the cam grooves and the cam pawls are provided with the same positional relationship with each other with respect to respective hand portions of the alarm and hour hands.
Accordingly, unlike the prior art in performing the work of attaching the hands of a clock having an alarm mechanism, according to the present invention, it is possible to attach an alarm hand and an hour hand onto respective shafts at any random position through a press-in mechanism or the like, without having to pay attention to the respective positional relationships of the two hands. When a setting alarm time is reached, the alarm and hour hands cooperate such that the cam grooves and the cam pawls are made to engage with each other resulting in a displacement which causes an alarm contact to be brought in an ON state due to the displacement to thereby generate an alarm sound.